1. Field of the Invention
The present disclosure generally relates to an electrophotographic toner and a method of preparing the electrophotographic toner.
2. Description of the Related Art
Polymerized toner has been drawing more attention for use in developing electrophotographic and electrostatic latent images as compared to pulverized toner. This may due to the market demand for high-quality, high-reliability, and high-productivity digital color multi-functional printers and color printers that use polymerized toner. With the growing concerns of global warming, there has also been a demand for high-quality polymerized toner having a wide color gamut, small particle size, narrow particle size distribution, and low-temperature fixing characteristics in order to reduce energy consumption and CO2 emissions.
Toner prepared by mixing and pulverizing processes has several limitations. In these processes, there is a limit to controlling toner structure and a huge amount of energy is required for preparing toner having smaller diameters. In addition, the cohesiveness and storage ability of pulverized toner may be degraded when a releasing agent, such as wax or a pigment, is exposed to the surface of toner. By contrast, polymerized toner may be obtained by aggregation and growth of source material particles and thus, it is straightforward to control the particle size distribution, circularity and morphology of toner. Polymerized toner also has higher resolution due to the ability to reproducibly form dots and lines and therefore, may be used in smaller amounts, thereby reducing energy consumption. Transfer efficiency and charging stability may also be improved with polymerized toner.
Polymerized toner is conventionally prepared by copolymerizing styrene and acrylate for use as the binder resin. Various applications for color resin require toner having high transparency and excellent low-temperature fixing characteristics. In order to improve these physical characteristics, methods for building a capsule structure including a core and a shell has been suggested. The suggested methods, however, may suppress the exposure of colorant to toner surface, thereby reducing the charge variation between different colors. If the amount of the releasing agent is high, a low-molecular weight releasing agent may be partially miscible with the resin, thereby causing toner to be plasticized. As a result, toner may have poor heat storage ability and flowability. For low-temperature fixing characteristics, methods for encapsulating a binder resin having a lower glass transition temperature (Tg) with a binder resin having a higher Tg has been suggested. However, the heat storage stability of toner prepared using these methods may not be satisfactory, although the toner may have low-temperature fixing characteristics.